Conventionally used transmissions for diesel railcars (diesel motor unit) include a torque converter for transmitting the power of an engine, multi-stage shift gears connected to the torque converter, and a wet type multiple disc clutch for switching the shift gears (see the publication of Registered Japanese Utility Model Application 2565596). A technique employed in transmissions for diesel railcars for enhancing transmission efficiency by using a mechanical clutch in place of the wet type multiple disc clutch is also suggested (see the publication of Japanese Utility Model Application Laid-Open No. Hei. 2-103555, and the publication of Japanese Patent Application Laid-Open No. Hei. 1-220761).
A twin-clutch type transmission for use in automobiles has been put into practical use in recent years (see publication of Japanese Patent Application Laid-Open No. 2003-269592, and Mitsubishi Motors Technical Review 2008 No. 20, pp. 31-34). Such a twin-clutch type transmission has already been used as a transmission for racing cars.
According to a hybrid technique suggested in recent years for transmissions for automobiles, a motor is provided in addition to an engine for assisting power with the motor during start or acceleration, and to generate electricity with the motor during deceleration.